Since the advent of complex motorized transportation systems, such as railroads, automobiles and airplanes, there has been a need to reduce or prevent noise caused by such systems from effecting surrounding neighborhoods and businesses. As highways increasingly are compelled to traverse residential areas, hospital zones and even industrial areas in which silence is a virtue, a problem arises with respect to the noise generated by the vehicles traveling on such highways. The problem is particularly pronounced as vehicle size increases and vehicle speed increases both for heavy vehicles and light vehicles.
Not only does the sound generated by traveling vehicles rank as an inconvenience to neighbors of such highways, but there is increasing evidence that continuous high noise levels associated with vehicle travel are detrimental to the health of individuals who dwell or work in the vicinity of highways, throughways, heavily traveled streets and avenues, and even carparks where both engine starting and wheel noise may be significant.
As such, in a growing number of transportation related settings, federal, state and local governments are specifying, supplying and installing sound barriers between roadways and the surrounding areas, particularly in areas of high traffic volume. Sound barriers are desirable in residential and commercial areas proximate interstate highways to attenuate noise in neighborhoods, shopping districts, and other commercial areas caused by traffic.
Therefore, there is a need for a noise barrier wall that has a high noise reduction coefficient yet also has a high sound transmission coefficient. Consequently, a number of devices and systems have been created which have been somewhat effective in alternating such noise.
Various materials are presently employed in the design and manufacture of various sound barriers. Prior art barrier designs constructed of steel, concrete, cement board, wood, and earthen barriers have been employed to effect a reduction of ambient noise levels proximate noisy roadways or construction sites. However, each have various disadvantages that make widespread production and installation impractical, either due to cost, manufacture and installation complexity, or poor sound attenuation.
Common barriers such as fences constructed of wood or a similar lightweight material probably served as the first noise barriers. While effective in preventing sight access, such barriers are quite ineffective in preventing the transmission of sound waves. Steel and metal barriers are prone to denting and chipping, as well as corrosion, and are extremely heavy. Wood barriers require periodic maintenance and have a comparatively short useful life. Concrete>barriers are very expensive to produce and install. Earthen barriers require a great deal of space to erect and are subject to erosion over time. Furthermore, each of these barrier designs requires labor intensive installation techniques, thereby placing a premium on product life. Additionally, none of the aforementioned barrier designs are particularly aesthetically pleasing, and all are susceptible to the application of graffiti and the like.
Therefore, there is a need for a sound barrier that is durable.
Concrete or masonry barriers and barriers constructed of a similar heavy material are perhaps more commonly used in attempting to prevent noise transmission. Barriers constructed of concrete are far superior to wood structures in accomplishing this goal, and yet it has been determined that concrete barriers and the like tend more to reflect sound waves rather than to dampen or absorb the same. Hence, while these types of barriers seem to be suitable for the accomplishment of some tasks along a highway or railroad track, they leave much to be desired in the area of preventing sound wave from being redirected or reflected onto people living in areas opposite a noise barrier wall installation.
Additionally, the installation of many prior art sound barriers requires an excess of installation hardware and complex mechanical hardware for assembling the barrier panels. Concrete and steel barriers require heavy equipment to place the barriers, and robust structural supports to hold the barriers in place due to their weight. Furthermore, the labor required to construct these barrier systems is quite costly.
Since many sound barriers are located adjacent to high speed motorways, there is a considerable possibility of impact between the barrier and a vehicle that is traveling at high speeds. As such, there is a possibility of damage to the barrier, which can cause considerable expense to correct. Furthermore, these structures are exposed to the elements, and as such, are susceptible to damage due to hail, as well as to freeze/thaw cycles. Again, repair of such damage can be quite expensive.
Therefore, there is a need for a sound barrier that is durable yet is economical to construct and erect, as well as to maintain.
Still further, since some of these structures are located near residential areas, fire may be a consideration both to protect the structures themselves as well as to protect nearby structures.
Therefore, there is a need for a sound wall that has a good fire rating.
Lately, much experimentation has been done with barriers having extruded members, particularly those which are modularly connected together, some of which are constructed of thermoplastic materials which absorb rather than deflect sound waves. Such structures may be effective in dampening much of the noise generated by highway traffic, locomotives, airplanes, and the like, although these barriers are not as effective as desirable. Furthermore, many of these barriers are constructed of materials which break down quickly or lose their resiliency when subjected to adverse conditions such as extreme weather and high-velocity impacts with foreign objects.
Some sound barriers use large quantities of rubber shavings contained within a hollow fiberglass panel in an effort to reduce sound reflection and/or transmission. However, it has been found that these structures are vulnerable to damage caused by changing weather conditions and vandalism. This type of barrier becomes a fire hazard in the event a vehicle crashes into the wall and spills fuel onto the wall.
Since sound barriers are often used to protect residential areas, hospitals, schools, and housing developments from high noise areas like roadways, construction sites, and shopping centers, the design and construction of economical and easily installed barriers is of particular import to quality of life in the modern world. Consequently, aesthetic appeal of such barriers has become a significant element in the design of such structures.
Therefore, there is a need for a sound wall that can be constructed in a manner that is aesthetically pleasing.
Still further, in any sound wall that has a sound absorbing layer bonded to a structural unit, the bond between the sound absorbing layer and the structural concrete layer is very critical. If the bond between the sound absorbing layer and the structural concrete layer is weak, the sound absorbing layer can dislodges from the structural concrete layer. Failure of the bond is dangerous because large pieces of the sound absorbing layer fall and endanger the general public. Consequently, many composite sound walls have become expensive and complicated to manufacture, difficult to erect, and expensive to maintain.
Therefore, there is a need for a sound wall that can be formed of several components, yet will be securely bonded to any structural element while still remaining efficient to manufacture, erect and maintain.